PEX to add Cast Iron Radiator (s)?

Old_Farmer

Good morning, all, I have a pretty straight forward question (s). My home was built in 2018 and has cast Iron Radiators. Furnace/boiler were replaced in 2012 and everything works fine. (I bought the home in 2018) My issue is that as I have remodeled, two old rooms off the side of my kitchen have been combined into 1 bathroom. it is about 12' long and 6' wide, they did not originally have any heating. I have an electric heater which I use in the winter, but it literally doubles my electric usage daily. (I have solar panels so I can track my consumption). I have one small Cast Iron Radiator, only 4 sections, about 2' tall, which may not be big enough for that space, but I can get a larger one if needed. My question is simple, I replumbed the entire house with PEX about 18 months ago and have had no issues and really like using the PEX, the last Radiator in line (before going back to the furnace is in the kitchen, (right beside the Bathroom). Can I use PEX and SharkBite's to add one new radiator into my bathroom? As I wrote this I also thought of another question, is that Radiator (described above) going to be big enough? (102sgft) I will not do this now as it os cold here n western PA, but it is a project I would like to do before next winter. Any advice would be greatly appreciated.

Old_Farmer

Quick correction, (I did spell check but not math check). The house was built in 1918, and the Bathroom is (72sqft). Sorry for any confusion.

GGross

Assuming your radiators are hot water and not steam
It's hard to say if the radiator is big enough to heat the space, but here is a thought. You could run the new supply and return lines and hook up that radiator, leave the electric heater in there but turn it off and if the radiator can't keep up you can turn on the electric. A quick glance at some random brands 4 section 2' tall radiators show you might expect to get 1000-1360 btu/hr from the radiator depending on your supply water temperature. The higher end of that output puts you at almost 19 btu/sqft which is pretty close to a guesstimate load for that space on a new construction. If it doesn't heat on the coldest days you can use the electric as backup. Not a big fan of sharkbites, however they have some use, just do not bury them in case you ever need to repair the connection. Some sharkbite installs last a long time, others not so much, considering you are using pex anyway you may be better off borrowing a tool to make the pex connections. Make yourself a drain point on the new supply and return with the ability to isolate the loop in case you need to make changes in the future, future you, and any service techs will thank you for it

ferrociousghandi

I agree with the above statement about shark bite fittings. I don’t recommend using them on heating. You can find radiator sizing charts online if you want something bigger but not overwhelming.